The present invention relates to voltage bias reference circuits, and, more particularly, to a circuit for coupling to the output of such reference circuits for suppressing high speed glitches that may appear at the output. Voltage bias reference circuits for providing a voltage bias signal to single or multiple utilization means are widely known. An example of a simple voltage reference circuit includes an NPN emitter follower stage the emitter of which is coupled to the output of the circuit for providing a reference voltage thereat in response to a predetermined current being supplied to its base. The output of the voltage reference circuit may be used to provide a bias signal to one or more loads coupled thereat.
In a typical application, the output reference voltage is utilized to provide biasing to the base of one transistor of a differential amplifier which receives a switching signal at the base of the second input transistor of the amplifier. The output of the differential amplifier will thus switch between first and second operating states whenever the applied switching signal passes above or below the reference voltage supplied to the one transistor as is well known. In some applications, multiple differential amplifiers may have one input thereof coupled to the output of the voltage reference circuit which are switched between operating states by respective switching signals. Due to base-emitter capacitive coupling through the differentially coupled transistors, it is possible to have high speed dV/dt signals appearing at the output of the voltage reference circuit due to the respective switching signals. If these dV/dt signals are sufficiently high in magnitude, the emitter follower stage of the voltage reference circuit can be turned off thereby increasing the output impedance of the circuit. This results in a glitch signal at the output of the reference circuit which is highly undesirable as the operating states of different ones of the multiple differential amplifier loads may then be incorrectly switched.
Thus, what is needed is a circuit for utilization with the voltage reference circuit for suppressing or severely reducing the aforementioned glitches.